Minimally invasive procedures have become increasingly popular for use in cardiac valve delivery, but there remain significant challenges in replacing a diseased cardiac valve without cardiopulmonary bypass. One is preventing cardiac failure during valve treatment while another is treating a valve without causing stroke or other ischemic events that might result the replacement procedure. Such downstream negative effects can be both immediate and delayed. For example, particulate material liberated while manipulating the native and prosthetic valves within the patient may result in embolization into distal vascular beds. Alternatively, such procedures may cause release of soluble mediators which cause the production and/or release of embolic debris. Accordingly, many patients suffering from cardiovascular disease have a higher risk of suffering from embolisms and greater care must be taken to minimize such risk in these patients.
There are four primary methods for providing embolic protection with catheter-based interventions. These include distal occlusion, distal filtering, proximal occlusion, and local plaque trapping. The occlusion methods involve occluding blood flow during target vessel intervention, then evacuating debris particles prior to restoring blood flow. While occlusion methods are simple and convenient, weaknesses of the methods include possible shunting of debris into side branches and the need for several minutes of end-organ ischemia caused by occlusion throughout the intervention. Distal filtering allows ongoing perfusion while trapping some debris, but the larger-diameter sheath generally required to maintain most filters in their collapsed state during advancement across the lesion, with potential dislodgement of debris, and reduced maneuverability of integrated-filter guidewire systems may pose significant problems.
It has not yet been definitively shown whether embolism protection is better achieved by occlusion or filtering methods. However, either would benefit from the development of devices and methods which decrease the inherent risk of embolism which accompanies percutaneous methods. Specifically, the potential damage which occurs upon passage of the devices through the vessels. Accordingly, it is desirable to refine all percutaneous devices to minimize this risk by means such as decreasing sheath diameters, increasing device flexibility and minimizing distance traveled by the device through the vessels. Disclosed herein are devices and methods for filtering embolic protection devices designed to minimize those risks inherent with percutaneous interventions,